Complications from the Misuse of Laxatives and Diuretics

The Misuse of Diuretics & Laxatives

Laxatives and diuretics are commonly misused by patients with eating disorders, particularly those with bulimia nervosa and the binge-purge subtype of anorexia nervosa. The misuse of laxatives and diuretics is a form of purging, which are methods to remove food consumed from the body to prevent weight gain or promote weight loss.

Eating disorder patients constitute the largest group of individuals who misuse laxatives, with up to 75% of those with anorexia and bulimia misusing laxatives and approximately 33% misusing diuretics. 

Many patients take laxatives to induce diarrhea to feel thinner, lighter or “empty.” Patients may also use laxatives to prevent the absorption of unwanted calories to lose weight or to avoid weight gain after binge eating. However, the effect on nutrient absorption is minimal, with only about a 12% reduction with use of laxatives.  Patients misuse diuretics with a similar purpose, to produce more urine to help eliminate water and achieve a lower body weight.

Why Diuretics and Laxatives are Misused

Complications of the Misuse of Diuretics and Laxatives 

Individuals with an eating disorder typically use stimulant laxatives, which stimulate the muscles of the gut to produce a bowel movement. Initially, an individual with an eating disorder might use laxatives to treat constipation or any number of other gastrointestinal complications that are caused by low food intake and dehydration.

However, over time the misuse of diuretics and laxatives can lead to a variety of issues ranging from dependency on these medications to complications that affect entire organ systems.

Laxative Dependence

A patient who abuses stimulant laxatives can become both psychologically and physiologically dependent on them, which can cause unpleasant and uncomfortable symptoms when individuals stop using them. Laxative abuse is frequently considered an addiction-like behavior.

Hypokalemia (Low Potassium)

Many of the severe medical complications of an eating disorder stem from electrolyte disturbances. Laxative misuse can result in chronic diarrhea, which in turn can cause fluid loss and hypokalemia, due to the high potassium in stool water and hormonal changes resulting from the intravascular depletion. Hypokalemia can cause:

• Neuromuscular dysfunction
• Gastrointestinal dysfunction, such as ileus and constipation
• Cardiac arrhythmias
• Inability of the kidneys to concentrate urine
• Sudden death

Hyponatremia (Low Sodium)

One of the main causes of hyponatremia is hypovolemia, which can result from the overall increased water loss stemming from diuretics and laxatives. Excess water consumption is also sometimes used to induce vomiting and can precipitate dangerous drops in serum sodium. Hyponatremia can cause:

• Nausea or vomiting
• Headaches
• Confusion
• Fatigue
• Seizures
• Muscle weakness

Metabolic Alkalosis

Metabolic alkalosis can occur as a result of either laxative or diuretic misuse, although laxative abuse itself can cause a significant loss of bicarbonate in the stools and cause a metabolic acidosis. When the body becomes dehydrated, up-regulation of a hormone called aldosterone occurs. Aldosterone has a few functions in the body, but one function is to cause more acid to be secreted in the urine, which throws off the body’s acid-base balance and creates more base (i.e. metabolic alkalosis).

Hypokalemia, which can result from diuretic and laxative abuse, can also cause hydrogen ions to shift into the body’s cells (in exchange for potassium), which will also throw off the acid-base balance and contribute to a metabolic alkalosis. Metabolic alkalosis alone is generally asymptomatic but may cause respiratory and neurologic changes.

PseudoBartter Syndrome

Purging behaviors with use of laxatives or diuretics (as well as vomiting) causes dehydration due to the fluid losses. These fluid losses cause up-regulation of certain hormones in the body, including aldosterone. The hyperaldosterone state that results from purging is great as it relates to helping maintain intravascular volume, which helps to lessen the risk of syncope (fainting). However, the increased aldosterone also causes salt and water resorption in the kidneys, contributing to the edema formation that can be so profound upon refeeding.

This increased aldosterone is also a contributor toward the cause of the hypokalemia and metabolic alkalosis mentioned above.

Kidney Disturbances

Prolonged laxative abuse is associated with chronic kidney disease. Renal function can be reduced by a combination of several factors, including the volume depletion that results from severe laxative abuse, hypokalemia, rhabdomyolysis and hyperuricemia (excess of uric acid in the blood).The repeated bouts of hypokalemia contribute to a condition called hypokalemic nephropathy, which may be irreversible and lead to chronic kidney disease or hemodialysis.

Hyponatremia & Central Pontine Myelinolysis (CPM)

Anyone that undergoes a rapid rise in serum sodium is at risk of developing central pontine myelinolysis, including those with eating disorders and those who misuse diuretics. CPM develops when the medical correction of hyponatremia occurs too abruptly, which causes various fluid shifts within the brain. Symptoms typically appear 2 to 3 days after hyponatremia is corrected, and include changes in cognition, dysarthria (trouble speaking), mutism or dysphagia (trouble swallowing). Within 1-2 weeks, other symptoms may manifest, including impaired thinking, weakness or paralysis in the arms and legs, stiffness, impaired sensation or loss of coordination. In the most severe cases, CPM can lead to coma or death.

There are no proven methods of treatment of CPM outside of supportive treatments, thus the need to avoid development of this complication in the first place. The actual mechanism by which CPM occurs is not fully understood, but the rapid increase in sodium concentration pulls water from brain cells which destroys myelin (a substance that protects nerve fibers) and sometimes the nerve cells themselves. The pons (the structure that links the brain to the spinal cord) is particularly susceptible to myelinolysis.

Cathartic Colon

Long-standing use of stimulant laxatives can result in the lower intestine (colon) becoming an inert tube incapable of peristalsis. Use of these stimulant laxatives damages one of the nerve layers of the intestine, causing the aperistalsis, which then creates a need for even greater amounts of stimulant laxatives. This condition is believed to resolve over time with discontinuation of the stimulant laxative use.

Laxative and Diuretic Misuse Treatment

Treatment for laxative and diuretic misuse are very similar, often involving patient education and addressing psychological dependency.

Laxative Misuse Treatment

The treatment for the misuse of laxatives is primarily psychological and targeted toward addressing a patient’s psychological dependency on laxatives and how that relates to their eating disorder. Physical dependency can be addressed through appropriate medical oversight to treat the electrolyte disturbances and edema formation, often through the use of prescribed diuretics in the early stages.

Education on Bowel Function

It can be challenging to convince patients to stop using laxatives. Due to the nature of eating disorders, a patient may not only be physically dependent on laxatives for bowel function but might also be psychologically dependent on laxatives and diuretics due to their anxiety around losing weight and misattributed feelings of weight control provided by laxatives.

Education is an essential tool in aiding a patient to cease laxative or diuretic misuse. Clinicians should aim to educate patients on the range of normal bowel function, which includes a minimum of three bowel movements per week as defined by the Rome III criteria. It’s also important to emphasize that laxatives are not an effective means of weight loss as most caloric absorption occurs in the small intestine, not in the colon, where laxatives function.

Treatment for Laxative Dependency

The only treatment for laxative and diuretic misuse is cessation. There is no medical benefit to tapering off laxatives, as ongoing exposure may cause ongoing damage to the nerves that contributes to the cathartic colon. Because of a patient’s dependence on laxatives, they may experience constipation. If constipation lasts for more than three days, a short course of a non-stimulating laxative combined with oral fluids should be used.

Daily polyethylene glycol, an osmotic laxative taken by mouth, should be started as soon as the patient stops taking stimulating laxatives. Occasionally, patients might require a glycerin suppository shortly after they stop taking laxatives. In rare instances, stronger laxatives may need to be used but this should only be done while monitored under a doctor’s care.

Treatment Timeline

After cessation of laxative misuse, a return to normal bowel function generally occurs within several weeks.

Diuretic Misuse Treatment

The treatment for the misuse of diuretics, similar to laxative misuse treatment, is primarily psychological and targeted toward addressing a patient’s psychological dependency on diuretics through therapy and education.

Treatment for Diuretic Dependency 

Unlike laxative dependency, physical dependency on diuretics is rare. However, a similar approach to treating laxative misuse should be taken regarding the psychological dependency a patient might have with diuretics and their relationship with these medications. Patients should be educated on the difference between water weight and weight from muscle or fat.

How to Stop Laxative Misuse

Stopping laxative and diuretic abuse will look a lot like treatment for an eating disorder. The care a patient receives will depend on the severity of complications and dependency on laxatives or diuretics. Letting go of a medication and behaviors associated with its misuse can be difficult and may require psychological guidance to overcome psychological dependency and address thought patterns that reinforce laxative and diuretic misuse.

Due to the impact laxatives and diuretics have on electrolyte levels, medication stabilization and monitored refeeding may be required to treat and avoid severe medical complications, including refeeding syndrome and central pontine myelinolysis. 

References

• Bulik CM. Abuse of drugs associated with eating disorders. J Subst Abuse 1992;4:69-90. 
• Bo-Linn GW, Santa Ana, CA, Morawski SG, et al. Purging and calorie absorption in bulimic patients and normal women. Ann Intern Med 1983;99:14-7.
• Forney KJ, Buchman-Schmitt JM, Keel PK, Frank GK. The medical complications associated with purging. Int J Eat Disord 2016;49(3):249-59.
• Gibson D, Benabe J, Watters A, et al. Personality characteristics and medical impact of stimulant laxative abuse in eating disorder patients---a pilot study. J Eat Disord 2021;9(1):146.
• Marino JM, Ertelt TE, Wonderlich SA, et al. Caffeine, artificial sweetener, and fluid intake in anorexia nervosa. Int J Eat Disord 2009;42(6):540-45.
• Mehler PS and Andersen AE (eds). 2022. Eating Disorders: A comprehensive guide to medical care and complications, 4^th ed. John Hopkins University Press.

Last Reviewed: November 2023 by Dennis Gibson, MD, FACP, CEDS